KR-102963390-B1 - MOTOR DRIVING APPARATUS AND METHOD

KR102963390B1KR 102963390 B1KR102963390 B1KR 102963390B1KR-102963390-B1

Abstract

A motor driving device for driving a motor having a plurality of windings corresponding to a plurality of phases is disclosed. The motor driving device includes: a first inverter including a plurality of first switching elements and connected to a first terminal of each of the plurality of windings; a second inverter including a plurality of second switching elements and connected to a second terminal of each of the plurality of windings; and a controller that synthesizes a vector corresponding to a voltage command of the motor using a switching vector that makes the difference between the common mode voltage of the first inverter and the common mode voltage of the second inverter zero, and controls the plurality of first switching elements and the plurality of second switching elements in a pulse width modulation manner based on the synthesized vector.

Inventors

정강호
신상철
하정익
최현규
심재훈

Assignees

현대자동차주식회사
기아 주식회사
서울대학교산학협력단

Dates

Publication Date: 20260508
Application Date: 20210720

Claims (5)

In a motor driving device for driving a motor having a plurality of windings corresponding to a plurality of phases, A first inverter comprising a plurality of first switching elements and connected to the first terminal of each of the plurality of windings; A second inverter comprising a plurality of second switching elements and connected to the second terminal of each of the plurality of windings; and A controller comprising: a switching vector that makes the difference between the common mode voltage of the first inverter and the common mode voltage of the second inverter zero, synthesizing a vector corresponding to the voltage command of the motor, and controlling the plurality of first switching elements and the plurality of second switching elements in a pulse width modulation manner based on the synthesized vector; The switching vector that makes the difference between the above common voltages zero is, A switching vector in which the switching state of the first inverter is [100] and the switching state of the second inverter is [010]; A switching vector in which the switching state of the first inverter is [100] and the switching state of the second inverter is [001]; A switching vector in which the switching state of the first inverter is [110] and the switching state of the second inverter is [011]; A switching vector in which the switching state of the first inverter is [110] and the switching state of the second inverter is [101]; A switching vector in which the switching state of the first inverter is [010] and the switching state of the second inverter is [001]; A switching vector in which the switching state of the first inverter is [010] and the switching state of the second inverter is [100]; A switching vector in which the switching state of the first inverter is [011] and the switching state of the second inverter is [101]; A switching vector in which the switching state of the first inverter is [011] and the switching state of the second inverter is [110]; A switching vector in which the switching state of the first inverter is [001] and the switching state of the second inverter is [100]; A switching vector in which the switching state of the first inverter is [001] and the switching state of the second inverter is [010]; A switching vector in which the switching state of the first inverter is [101] and the switching state of the second inverter is [110]; and A switching vector comprising [101] switching state of the first inverter and [011] switching state of the second inverter, wherein A motor driving device characterized in that the first digit of the number indicating the switching state represents the switching state of the switching element of phase a in the first inverter and the second inverter, the second digit represents the switching state of the switching element of phase b, and the third digit represents the switching state of phase c, wherein the number '1' indicates that the upper switching element of the corresponding phase is in the ON state and the lower switching element is in the OFF state, and the number '0' indicates that the upper switching element of the corresponding phase is in the OFF state and the lower switching element is in the ON state.
In claim 1, the controller is, A switching vector in which the switching state of the first inverter is [100] and the switching state of the second inverter is [011], a switching vector in which the switching state of the first inverter is [110] and the switching state of the second inverter is [001], a switching vector in which the switching state of the first inverter is [010] and the switching state of the second inverter is [101], a switching vector in which the switching state of the first inverter is [001] and the switching state of the second inverter is [100], and a switching vector in which the switching state of the first inverter is [001] and the switching state of the second inverter is [110] are not used to synthesize a vector corresponding to the voltage command, A motor driving device characterized in that the first digit of the number indicating the switching state represents the switching state of the switching element of phase a in the first inverter and the second inverter, the second digit represents the switching state of the switching element of phase b, and the third digit represents the switching state of phase c, wherein the number '1' indicates that the upper switching element of the corresponding phase is in the ON state and the lower switching element is in the OFF state, and the number '0' indicates that the upper switching element of the corresponding phase is in the OFF state and the lower switching element is in the ON state.
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In claim 1, the controller is, A motor driving device characterized by synthesizing a voltage command vector using two switching vectors adjacent to the voltage command vector of the motor among the switching vectors that make the common mode voltage difference zero.
In claim 4, the controller is, A motor driving device characterized by expressing the above voltage command vector as the sum of values obtained by multiplying each of two switching vectors adjacent to the voltage command vector of the motor by a constant coefficient, and determining the duty of space vector pulse width modulation based on the coefficient.

Description

Motor Driving Apparatus and Method The present invention relates to a motor driving device, and more specifically, to an open-end winding type motor driving device in which an inverter is connected to each end of the motor winding. Generally, one end of each phase winding included in the motor is connected to a single inverter, and the other ends are connected to each other to form a Y-connection. When driving the motor, the switching element in the inverter is turned on/off by pulse width modulation control, and torque is generated by applying line voltage to the windings of the Y-connected motor to generate alternating current. Since the fuel efficiency (or electric efficiency) of eco-friendly vehicles, such as electric vehicles that utilize torque generated by such motors as power, is determined by the power conversion efficiency between the inverter and the motor, it is important to maximize the power conversion efficiency of the inverter and the efficiency of the motor to improve fuel efficiency. The efficiency of an inverter-motor system is primarily determined by the voltage utilization rate of the inverter; if the vehicle's operating point, determined by the relationship between motor speed and torque, is formed in a range of high voltage utilization, the vehicle's fuel efficiency can be improved. However, increasing the number of windings to boost maximum torque causes the high-voltage utilization region to move further away from the low-torque region, which is the vehicle's primary operating point, potentially leading to poor fuel efficiency. Furthermore, designing the motor to include the primary operating point within the high-voltage utilization region for the sake of fuel efficiency may result in limitations on the motor's maximum torque, which can lead to reduced acceleration performance. To solve this problem, an Open End Winding (OEW) motor driving technique has been proposed in the field of technology, in which two inverters are driven by connecting an inverter to each end of the motor winding instead of short-circuiting one end of the motor winding through a Y connection. This open-end winding motor driving technique has the advantage of being able to increase phase voltage to improve voltage utilization and enable high output compared to the method of driving a conventional Y-connected motor. However, in open-end winding motor drive techniques, circulating current can occur due to the difference in common-mode voltage of the inverters connected to each end of the motor winding. This circulating current flows through the motor windings and acts as a loss, such as copper loss and iron loss, causing problems that reduce motor efficiency. The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. FIG. 1 is a circuit diagram of a motor driving device according to one embodiment of the present invention. Figure 2 is a diagram showing the voltage vectors of each of the two inverters when controlling an open-ended winding motor using a space vector pulse width modulation method. Figure 3 is a diagram illustrating the voltage vector combined by two inverters when driving a motor using an open-end winding method. Figure 4 is a simplified vector diagram of the vector diagram shown in Figure 3, excluding the voltage vector that generates the common mode voltage difference between the two inverters. FIGS. 5 and 6 respectively illustrate the inverter phase current when space vector pulse width modulation is performed using a switching vector having a common mode voltage difference and the inverter phase current when space vector pulse width modulation is performed using a switching vector in which the common mode voltage difference is eliminated. Hereinafter, a motor driving device according to various embodiments of the present invention will be described in detail with reference to the attached drawings. FIG. 1 is a circuit diagram of a motor driving device according to one embodiment of the present invention. Referring to FIG. 1, a motor driving device according to one embodiment of the present invention is a motor driving device that supplies driving power to a motor (100) having a plurality of windings (L1-L3) corresponding to a plurality of phases, and may be configured to include a first inverter (10) connected to a first terminal of each winding of the motor (100) and including a plurality of first switching elements (S11-S16), a second inverter (20) connected to a second terminal of each winding of the motor (100) and including a plurality of second switching elements (S21-S26), and a controller (30) that controls pulse width modulation of the first switching elements (S11-S16) and the second switching elements (S21-S26) based on the required output of the motor (100). The first inverter (10)